Conventionally, in a transforming apparatus such as the GIS, an intermediate electrode is provided between a central conductor and a tank to constitute a voltage divider, and the voltage of the central conductor is detected based on the voltage of the voltage divider. In such a voltage detection device for a transforming apparatus, a high-pass filter is formed by a floating electrostatic capacitance between the central conductor and the intermediate electrode, an earth electrostatic capacitance between the intermediate electrode and the tank, and a secondary resistor connected in parallel to the earth electrostatic capacitance. An output waveform of the voltage divider becomes a time derivative waveform of a voltage waveform of the central conductor. Therefore, a voltage signal proportional to temporal differentiation of a primary voltage generated in a main conductor is acquired from an output terminal, and integration treatment is performed with respect to the acquired voltage signal to acquire a voltage signal proportional to the primary voltage. The acquired voltage signal is analog-digital converted to acquire digital data proportional to the primary voltage (for example, Patent Literature 1).